1. Technical Field
The present disclosure relates to imaging systems and, particularly, to a computational imaging system.
2. Description of Related Art
Generally, an image of an object captured by conventional imaging systems is in focus only over a limited object distance range which is known as depth of field (DOF). Therefore, it is difficult to sharply capture object scenes that span large distances. To obtain an extended DOF, one attempt has been made that deliberately blurs an intermediate image captured by an imaging system by placing a coded aperture in the aperture of the imaging system and then digitally removes the blur using reconstruction algorithms. The coded aperture is patterned according to a modulation transfer function (e.g., a delta function). As such, reconstruction algorithms can effectively deconvolute the modulation transfer function and restores the image to a more recognizable likeness of the object with a greater DOF than what that would have been otherwise obtainable. This is known as coded aperture imaging and is one kind of computational imaging system. See Zand, J., “Coded Aperture Imaging in High Energy Astronomy”, NASA Laboratory for High Energy Astrophysics (LHEA) at NASA's GSFC (1996); Levin, A., Fergus, R., Durand, F., Freeman, B., “Image and Depth from a Conventional Camera with a Coded Aperture”, ACM Transactions on Graphics (Proc. SIGGRAPH) (2007); Veeraraghavan, A., Raskar, R., Agrawal, A., Mohan, A., Tumblin, J., “Dappled Photography: Mask Enhanced Cameras for Heterodyned Light Fields and Coded Aperture Refocusing”, ACM Transactions on Graphics (Proc. SIGGRAPH) (2007); and Liang, C. K., Lin, T. H., Wong, B. Y., Liu, C., Chen, H. H., “Programmable Aperture Photography: Multiplexed Light Field Acquisition”, ACM Transactions on Graphics (Proc. SIGGRAPH), Vol. 27, No. 3, Article No. 55 (2008). However, to blur the intermediate image, the coded aperture (e.g., the pattern formed on the coded aperture) also blocks large amounts of light rays incident on the aperture, resulting in large amount of light loss.
Therefore, it is desirable to provide a computational imaging system, which can overcome the abovementioned shortcomings.